Handley Page HP.43
The HP.43 was tendered to specification C.16/28 for a three engined bomber / transport. Only one was built, J9833, with three uncowled Bristol Pegasus IM3 radial engines, and it first flew on 21 June 1932.
It had heavy and badly harmonised controls and poor performance, and was converted into the HP.51 twin engined monoplane to C.26/31.
Gustav Lachmann took on the technical development of modern methods of aerodynamics and metal construction, and went on to convert the H.P.43 biplane into the H.P.51, with a modern monoplane wing and aircooled engine nacelles. This led to the order for 100 of a production version, the H.P.54 Harrow.